To investigate experimentally the extension of a spring and how it is related to the applied force, and recall that the extension of a spring is directly proportional to the force applied, provided ...

The mass is just sitting there motionless. There is no acceleration and it is in equilibrium. What does this mean? This means that the net force in the y-direction (vertical direction) must be zero. I ...

Let's pick a lab. Maybe it is a lab that looks at masses oscillating on a spring. In this lab, students could put different masses on the end of a spring and let it oscillate up and down.